BIL & fiancé not being responsible or respectable

Hi,
My BIL & his fiancé (they are 32yr old & 38yr old-old enough to know better) & their 2x make dogs are staying at our place. In the beginning we (Myself, hubby & female dog) stayed at their place (much appreciative of them for offering) for 5 months while we searched for a rental. So we found our own rental in February and moved into our new place. Mid April they suddenly announce that their moving from their place because they recon the landlord is going to up the rent ($80) way too much (in the end the rent only went up by $20 but they didn’t bother to ask how much it would be rising by before ending the lease....who knows why?!) so my hubby & I agree we can return the favour and they can stay with us until they find a rental (all approved by our landlord)
10 months in we are desperate for them to leave. They don’t always clean up after themselves, their 2 male dogs pee on EVERYTHING and any mess they make, they assume/expect that we’re going to clean it up!. Earlier on we cleaned up their mess a couple of times and after that they assumed we would do it everytime. (They both work away and leave dirty dishes & other mess lying around the night before their due to leave & we wake up in the morning expecting that they have cleaned it up- and they haven’t so we are forced to clean up as their gone for 2 weeks at a time) so just had a massive row with them tonight because they left a pile of rubbish (Which we left for THEM to clean up) and grot on the ground and Tonight discovered the male dogs peed all over it like 2 weeks ago...the stench? Well 2 week old male dog piss. Once we realised it had that over it we asked them to clean up after their own dogs and they reluctantly did but then stated that ‘it’s not their fault the dogs like to mark their territory- it’s not our fault there’s a female dog around’ - turning the blame onto our dog and went as far as to say that our dog was peeing on everything, not theirs. (Our dog is a female who squats to pee and can’t cock her leg up and she’s never peed on something purposely because we properly trained her to know this.) & we’ve seen both their dogs cock their leg and pee on things multiple times. To add:
Safe to say the house reeks of dog pee, they get free internet, cheap ass rent and their dogs looked after for free while their both away for 2 weeks at work. We have to clean up after them & their dogs because they leave mess right before they leave, they don’t respect us or our home and they have the audacity to whinge & question going halves in the power bill, whinge that they don’t get a set of keys to our place (my hubby works from home; is always home) whinge because we have household rules that they don’t like, blame things they/ their dogs did, on us and our dog, don’t respect us and plain & simple, don’t care. We respected their place & boundaries when we stayed at theirs, cleaned up after our dog (she’s not a messy dog so there wasn’t much to do) it’s like they just pay us the rent and that wipes their hands if any responsibility. We want them gone but my hubby says ‘his my brother, I can’t kick him out and they let us stay at their place when we needed help’ yes we stayed at theirs & we’re extremely grateful for their help, BUT difference is; we were respectful of their home & cleaned your after ourselves. WTF do we do guys? Not kick them out & encourage them to not have ridiculous standards and just find a bloody rental! Yes it’s hard to find rentals but is made harder with her requirements : (their minimum was secure double garage for vehicles and sturdy safe yard for dogs- that’s fine, that’s warranted....(but fiancé’s requirements are ‘needs two bathrooms, toilets have to be separate, has to have double vanity in each, has to have a spa or at least big bath tub & the kitchen has to be like a showroom.’ For how much rent they want to pay per week ($350) they won’t be getting all that... rentals like that are $450-650 here....) WE ARE OVER IT!